What is the difference between the hvx-200 1/3 chip and hpx-500 2/3 chip in sensitivity to low light - in f stops? I am proposing some early morning and late afternoon mood shots from a helicopter. I need speed. Are there any supplementary programs to compliment fcp 6 in this process?

The HPX500 is at least 1.5 stops faster than an HVX200.